Rod Coupling Assembly and Methods for Bone Fixation

• US 20090105770A1
• Filed: 10/23/2008
• Published: 04/23/2009
• Est. Priority Date: 10/23/2007
• Status: Active Grant

• Current Assignee: Pioneer Surgical Technology Incorporated (Surgalign Holdings, Inc.)
• Original Assignee: Pioneer Surgical Technology Incorporated (Surgalign Holdings, Inc.)
• Inventors: Berrevoets, Gregory, Perrow, Scott J.
• Granted Patent: US 8,398,683 B2
• Time in Patent Office: Days
• US Class Current: 606/308
• CPC Class Codes: A61B 17/70 Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
• CPC Class Codes: A61B 17/7001 Screws or hooks combined with longitudinal elements which do not contact vertebrae A61B17/7058 takes precedence
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7035 Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7049 Connectors, not bearing on the vertebrae, for linking longitudinal elements together A61B17/7055, A61B17/7053, A61B17/7019 take precedence
• CPC Class Codes: A61B 17/88 Osteosynthesis instruments; Methods or means for implanting or extracting internal or external fixation devices A61B17/7074 takes precedence

Abstract

A coupling device for securing an elongate member to the spine is provided. The coupling device comprises a compressible inner member that secures an anchor member therein when the inner member is axially shifted within an outer member. Structures are provided to prevent disassembly of the anchor and coupling device prior to locking of the elongate member.

Claims

1. An assembly for securing an elongate member to the spine, the assembly comprising:

an anchor member having a head portion;

an insert member with a lower portion having a plurality of flexible walls forming a cavity for receiving the anchor head portion;

an outer member having an inner surface defining an inner space for receiving the insert member, the inner surface having at least a portion configured to shift the insert member walls against the anchor member head in order to fix the anchor member head at an angular position with respect to the insert member;

a retention mechanism comprising at least one feature on the outer member that interacts with at least one corresponding feature on the insert member to retain the insert member at least partially within the internal space of the outer member.

2. The assembly of claim 1 wherein the retention mechanism comprises at least one protrusion on the outer member and at least one protrusion on the insert member, the insert member protrusion configured to shift relatively easily past the outer member protrusion in a first direction and to resist movement past the outer member protrusion in a second direction.

3. The assembly of claim 1 wherein the retention mechanism comprises an outer member protrusion having a ramped portion and a flat portion and an insert member protrusion having a ramped portion and a flat portion;

wherein the ramped portion of the insert member protrusion is configured to engage the ramped portion of the outer member protrusion when the insert is linearly inserted into the internal space of the outer member so that the ramped surfaces slide past one another as the insert is shifted in a first direction; and

wherein the flat portion of the insert member protrusion is configured to engage the flat portion of the outer member protrusion to resist movement in a second direction opposite from the first direction.

4. The assembly of claim 1 wherein the retention mechanism comprises a protrusion located on a flexible portion of the insert member and a protrusion located on the outer member, the protrusions configured so that the flexible portion having the insert member protrusion is shifted to allow the insert member protrusion to bypass the outer member protrusion when the insert member is shifted in a first direction.

5. The assembly of claim 4 wherein the protrustions are configured to abut without shifting of the flexible portion when the insert member is shifted in a second direction.

6. The assembly of claim 1 further comprising:

an upper portion of the insert member having arms to receive the elongate member therebetween; and

a rod lock member configured to fix the elongate member in place relative to the coupling assembly.

7. The assembly of claim 1 further comprising:

A surface contour of the outer member interior surface configured to shift the lower walls of the insert portion toward one another to prevent the anchor head from exiting the insert member interior space when the insert member is shifted to a first retention position within the interior space of the outer member, the surface contour further configured to shift the lower walls of the insert portion toward one another to frictionally lock the anchor head therebetween at a fixed angle when the insert member is linearly shifted to a second lock position;

a protrusion located on the insert member positioned and configured to engage a protrusion on the outer member when the insert member is shifted into the first retention position;

the insert member protrusion and outer member protrusion configured to prevent movement of the insert member in a second direction after insertion of the insert member to the retention position in a first direction.

8. The assembly of claim 7 further comprising:

an upper portion of the insert member having arms to receive the elongate member therebetween, at least one of the arms having first and second spaced apart retention protrusions;

first and second retention protrusion on the outer member corresponding to the protrusions on the at least one arm of the insert member; and

a rod lock member configured to wedge fit between the outer member and the at least one arm of the inner member to shift the at least one arm against the elongate member to frictionally lock the elongate member in place.

9. The assembly of claim 7 wherein the at least one arm is able to shift to permit the insert member protrusions to slide past the outer member protrusions when the elongate member is not received between the arms, but is not able to shift to permit the insert member protrusions to slide past the outer member protrusions when the elongate member is received between the arms.

10. An assembly for securing an elongate member to the spine, the assembly comprising:

an anchor member having an anchoring portion and a head portion, the head portion having a height, a first head width, and a second head width, the first head width greater than the second head width;

an anchor receiving member having an internal space for receiving the head of the anchor member;

an opening in the bottom of the anchor receiving member, the opening having a shape that permits the anchor head to shift into and out of the internal space when the anchor head is in a first orientation relative to the opening but resists shifting of the anchor head into and out of the internal space when the anchor head is in a second orientation.

11. The assembly of claim 10, wherein the elongate member is received in an upper portion of the anchor receiving member.

12. The assembly of claim 10, wherein the anchor receiving member includes a plurality of resiliently deflectable grasping members forming the opening, the deflectable members configured to be deflected away from one another to receive the anchor head in the first orientation and to resiliently shift toward one another to grasp the anchor head in either the first orientation or the second orientation.

13. The assembly of claim 12, wherein the anchor receiving member is an insert member configured for linear insertion into an internal space of an outer member.

14. The assembly of claim 13, wherein the elongate member is received in an upper portion of the insert member.

15. The assembly of claim 12, wherein the outer member internal space is configured to deflect the plurality of lower insert portions toward one another to fix the anchor head at an angular position with respect to the insert member when the insert member is linearly inserted to a predetermined depth into the internal space of the outer member.